Sandbagging and other preparations were being made in neighborhoods under threat, while heavy rains caused more than 260,000 power outages and dozens of voluntary evacuations in parts of central and Northern California.

Several inches of rain had already fallen in some mountainous areas in the north by Tuesday afternoon. But precipitation was still relatively light in the south, where flood watches were issued in fire-ravaged parts of Santa Barbara and Los Angeles counties as the storm was expected to strengthen by nightfall.

“It’s something we prepare for every year,” Los Angeles County fire Inspector Frederic Stowers said. “We know the fires go through and do a lot of damage. Within L.A. County, much of the slopes burned are going to be critical.”

People living around burn areas near the 250-square-mile Station Fire in Angeles National Forest were warned to brace for possible flows of mud, ash and debris with rainfall of up to 4 inches. Los Angeles County‘s average rainfall for October is less than half an inch.

The storm was expected to drop 3 to 6 inches of rain in Santa Barbara County, where an 8,700-acre fire burned in May, before it moves on to the San Gabriel Mountains, where the U.S. Geological Survey recently warned of massive debris flows near the areas burned in September.

“It is obvious to me there are going to be some slides,” said Richard Payatt, 46, whose Santa Barbara home was evacuated during the fire in May. “It’s part of living in Santa Barbara with these beautiful hills. Occasionally you get fires, and then you get slides.”

Payatt said a local hardware store was sold out of tarps and sandbags because of the storm.

Flash flood watches were issued for 11 counties up and down the state, said National Weather Service meteorologist Todd Morris.

The agency issued a flash flood watch through Wednesday for the Santa Barbara burn areas. Between 1 and 2.4 inches of rain fell through Tuesday afternoon, Morris said. A flash flood watch for the Los Angeles-area foothills was to take effect at 6 p.m. Tuesday.

Stowers said thousands of sandbags were distributed to fire stations throughout Los Angeles County, including more than 10,000 at a station near La Canada Flintridge.

Areas of concern in Los Angeles County include Tujunga, La Crescenta and La Canada Flintridge.

In Northern California, forecasters issued high wind warnings for the mountains, where gusts up to 60 mph were expected, and advisories for lower elevations, where gusts were expected to reach 50 mph.

By midday Tuesday, more than 6 inches of rain had fallen in parts of the Santa Cruz Mountains and more than 4 inches in parts of Marin County, according to the National Weather Service.

“There’s an awful lot of moisture in this system falling pretty heavily in quite a few places,” National Weather Service forecaster Diana Henderson said. “With it being the first significant system of the rain season, drains are backed up, oil and other materials are starting to rise on the streets. It’s just ugly out there.”

Geologist Mathers Rowley lives in the Swanton Road area where the voluntary evacuations were under way. He said he did not plan to leave right away as his house was in a safe position.

“If I lived in another tributary nearby, I wouldn’t be here. There are some really steep denuded slopes that with the wind and rain could send debris straight down. But it hasn’t developed where I am. If it gets worse, then we’ll see,” he said.

Crews nearby were bagging 25 tons of sand for people to use to shore up their homes.

State fire spokeswoman Colleen Baxter said the biggest concern was if the rainfall increases, mud and debris will slip down the hillsides made bare from the summer fire.

“The ground was left unprotected,” she said. “That instability combined with the rain, you worry about slippage.”

The American Red Cross set up an evacuation center nearby.

High winds knocked out power to about 263,000 Pacific Gas & Electric customers in central and northern California, but crews have managed to restore power to more than half of those customers, said utility spokesman Joe Molica. In the greater San Francisco Bay area, 23,000 customers remained without power at 1 p.m.

Authorities were warning motorists to drive slowly over San Francisco Bay area bridges because of stormy conditions.